Management of rice production systems to increase productivity

4.1. General conclusions
CHAPTER FOUR:
GENERAL RESEARCH SUMMARY
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The challenge faced by African farmers while managing a fragile
natural resource base is to increase food production to feed a still increasing
population. To increase rice production, a sustainable production system that
optimizes land resource use while economizing on water and agrochemical
requirements needs to be available. Apart from maintaining sustainable soil
fertility, the complexity of upland rice environment is such that genotypic
improvement and management studies to increase and maintain a stable grain
yield should take into consideration other components of the upland rice
environments such as drought, pest and disease complexes, etc. In the
lowland, the major causes of yield reduction are poor water control, nutrient
deficiency, water borne‐pests, low nutrient use efficiency resulting from
continuous flooding, and inconsistent planting calendar.
This study made possible the identification of low‐input upland rice
cultivars, as well as improved lowland rice management practices that can
greatly increase rice yields using small amounts of inorganic fertilizer and/or
organic soil conditioners such as compost or green manure.
Although the low‐input upland cultivars may have a high NUE, the
amount of nutrients available in continuously cultivated lands is not sufficient
to support high crop productivity. This study showed that the recommended
low‐input fertilizer application rate is too low to support optimum rice
productivity. However, if the low‐input varieties are grown with 80‐40‐40